Enhancing catalytic performance of TiO2/P-doped C3N4 composite via preferentially bonded P-O-Ti

Optimizing photocatalyst structure at the atomic level is a crucial challenge in improving photocatalytic performance. Herein, a series of TiO2/P-doped C3N4-pinned composites have been synthesized to optimize photocatalyst structure at the atomic level. Among the nonmetals (P, C, and N) in P-doped C3N4 (CN-P), TiO2 preferentially bonds with P to form stable P-O-Ti chemical bonds that can act as efficient carrier transfer channels. Comprehensive correlations between P-O-Ti bond features, defects, carrier kinetics, and photocatalytic activity have been studied theoretically and experimentally. Photocurrent-time curves and distribution of relaxation times analysis reveals that preferentially bonded P-O-Ti improves carrier separation and transfer. The special P-O-Ti interface bonds endows composites TiO2/P-doped C3N4 with multifunctional photocatalysis properties, i.e., hydrogen production (815 µmol g−1 h−1), and reduction in heavy metal ions Cr (VI) (7 min, 100%) under visible light (λ > 400 nm) irradiations, which outperforms most of existing CN-P and TiO2 composite catalysts, as well as excellent degradation performance for organic contaminants. More importantly, the composite with optimal composition shows a superior stability and repeatability in ten cycles of testing. These findings provide valuable hints in optimizing photocatalyst structure at the atomic level for enhancing carrier dynamics and improving photocatalytic performance necessary for applications under visible light.